In agriculture, is it conventional to apply fertilizer, plant protectants and other substances which promote plant growth over the arable land in particular in an aqueous suspension or solution by means of a spraying device. The spraying device is generally arranged on a vehicle in this case and typically comprises a storage container for the substance to be sprayed, a pump for generating the spraying pressure, valves for controlling the quantity to be sprayed and a spray bar which projects over part of the arable land transversely to the direction of travel, and a plurality of nozzles arranged at a spacing from one another, to which the spray substance is supplied at a pressure that is suitable for forming an atomizing cone. A vehicle intended for agricultural use having a spraying device is known from DE 696 25 914 T2.
In agricultural spraying, it is important to spray the spray substances uniformly and in the desired or specified amount, and to avoid non-uniform spraying patterns since they can adversely affect the crop yield. The divergent spray jets or atomizing cones generated by the individual nozzles of the spraying device are particularly essential to uniform spraying. The spray substance which reaches the field area is only uniformly distributed in the longitudinal direction of the spraying bar if these jets or cones have an identical and correct formation at every nozzle. Uniform distribution over the area depends on the speed of the vehicle carrying the spraying device staying the same.
If individual nozzles are defective, for example as a result of wear or the deposition of particles, an incorrect atomizing cone can form and can thus affect the required uniform distribution of the spray substance. There is therefore a need to test the functions of an agricultural spraying device, in particular with regard to the generation of the atomizing cone by the nozzles.
DE 198 29 594 C2 discloses a method for determining the distribution quality of hydraulic or hydraulic-pneumatic nozzles over an entire plane to which an atomizing cone is applied by the nozzle. According to this method, the extent to which collecting containers arranged next to one another in a row in one plane are filled, is measured by the spray jet of the nozzle, the nozzle and the row of collecting containers being rotated relative to one another by a defined angle about the central axis of the nozzle. The distribution quality of the nozzle can then be calculated from the extent to which the individual containers are filled. The known method is suitable for testing individual nozzles under laboratory conditions. In order to test the nozzles of an agricultural spraying device quickly, said method is, however, too complex.
Furthermore, a method for determining the pattern and the quantity parameters of fuel nozzles used in gas turbines is known from WO 2007/106982 A1. In a variant of the method described herein, the atomizing cone of a nozzle is cut perpendicularly to the central axis by means of a planar laser beam and an optical image of the droplets of the atomizing cone, which droplets scatter the light of the planar laser beam, is captured by a digital camera. The image of the cross section of the atomizing cone that is lit up by the laser beam, which image is recorded by the camera and displayed on a screen, shows variations in the light intensity, high light intensity corresponding to high radiance. In order to calculate the spraying parameters, the distribution of the light intensity of the recorded image can then be divided into zones and evaluated similarly to with a mechanical patternator.